Luminescent properties of sol–gel processed red-emitting phosphor Eu³⁺, Bi³⁺ co-doped (Ca,Sr)(Mo,W)O₄

Abstract

A series of red-emitting phosphors Ca_0.6Sr_{0.4−1.5y−1.5z}Mo_1−xW_xO₄:Eu_yBi_z (x = 0–1, y = 0–0.14, z = 0–0.12) have been synthesized by a sol–gel method. The effects of calcining temperature, concentrations of Bi³⁺ and Eu³⁺, and the W/Mo ratio on the luminescent properties were investigated. X-ray diffraction and scanning electron microscopic results showed that as-prepared phosphors were of single phase with several microns. The Bi³⁺ and Eu³⁺ co-doped phosphors showed remarkably intense red emission at 618 nm. The emission intensities of the series reached maximum for compositions at x = 0.4, y = 0.12 and z = 0.08 when the calcining temperature was 900 °C. Temperature dependent emission intensity of the phosphor suggested that the as-synthesized product had good thermal stability with a thermal quenching activation energy of 0.31 eV. The decay curves showed the energy transfer efficiency from MoO₄ ²⁻ to Eu³⁺ increased with an increase in the Mo⁶⁺ doping content.